Acid-treated nanotubes

SWNTs are readily opened by mild treatment with acids and filled with metals [45, 132]. Acid-treated nanotube surfaces can be decorated by nanopartides of metals such as Au, Ag or Pt [45, 133]. 

It seems that the pristine nanotube results are somewhat controversial. The alignment effect is observed with the pristine nanotubes, however, it shouldn t be observed. We are collecting more samples, such as purified nanotubes, Ni-coated nanotubes, strong-acid-treated nanotubes, which will be tested at NASA Ames Research Center. It is expected that with more samples, we will better understand the relationship between conductivity and structure. 

Acid-treated nanotubes can also be used to electrochemically deposit metal (e.g., gold) nanoparticles onto CNT surfaces [61-62]. 

Porter, A.E. et al. (2009) Uptake of noncytotoxic acid-treated single-walled carbon nanotubes into the cytoplasm of human macrophage cells. ACS Nano,... 

The acid reflux procedure was first described by Rinzler el al. [28], in which raw nanotube materials are refluxed in nitric acid to oxidize the metals and carbon impurities. Acid-treated CNTs are considered to have carboxylic acid groups at the tube ends and, possibly, at defects on the side walls. The functionalized SWNTs have considerably different properties from those of the pristine tubes. 

J.Y. Kwon, H.D. Kim, Preparation and properties of acid-treated multiwalled carbon nanotubes/waterborne polyurethane nanocomposites, Journal of Applied Polymer Science, vol. 96, pp. 595-604, 2005. 

C C.ImllBFJ Acid-treated multiwalled carbon nanotube GCE Hemin, Hb horseradish peroxidase H2O2 NR NR Cyclic voltammograms 34 s S ... 

Kwon et al. compared WPU/MWNT with WPU/nitric acid treated multiwalled carbon nanotube (A-CNT) composites (20). The tensile strength and modulus of the WPU/A-CNT composites were higher than those of the WPU/MWNT composites with the same CNT content. The better mechanical properties of WPU / A-CNT composites can perhaps be attributed to higher content of polar groups of A-CNTs thus inducing higher interfacial interactions between A-CNTs and WPU chains. 

The wrapping process is typically carried out in liquid medium a PEI chloroform solution (1.5% w/w) is mixed with the SWCNTs under intense stirring. The blend is then treated with an ultrasonic tip for 1 h at 50% oscillation amplitude and 50% cycle time. The resulting dispersion is subsequently filtered using a 0.2 pm pore size PTFE membrane and dried under vacuum at 60°C to assure total evaporation of the solvent. The wrapped SWCNTs can be characterized by different techniques, and some results are included in Table 10.1. Figure 10.5 shows TEM images of acid-treated SWCNTs dispersed in the compatibilizer. Small nanotube bundles shrouded in PEI can be visualized in the micrographs. 

Carbon nanotubes (CNTs) can be used as templates for conducting polymers. Composite films of CNTs with PANl, PPy, or PEDOT were prepared via electrochemical codeposition from solutions containing acid treated CNTs and the corresponding monomer [192], Electrochemical synthesis of PPy/CNT nanoscale composites using well-aligned carbon nanotube arrays was reported [193]. 

Bikiaris, D., Vassiliou, A., Chrissafis, K., Paraskevopoulos, K. M., Jannakoudakis, J., and Docoslis, A. 2008. Effect of acid treated multi-walled carbon nanotubes on the mechanical, permeability, thermal properties and thermo-oxidative stability of isotactic polypropylene. Polymer Degradation and Stability 93 952-967. 

Functionalized multi-walled carbon nanotubes (MWNTs) were prepared by acid treatment followed by reaction with 3-aminopropyltriethoxysilane. Reaction of silane with oxidized nanotubes was confirmed by Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray (EDX) analysis to confirm silicon on the surface of the MWNTs. Raman spectroscopy of the acid-treated MWNTs confirmed formation of surface defects due to carboxyl... 

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